Reset Service Tag in BIOS Dell OptiPlex 3040 SFF

[DavR]

Has anyone had any luck resetting the service tag on the motherboard of a Dell OptiPlex 3040 or similar vintage machine? I'm replacing the motherboard with a second hand spare and would like my serial numbers to align properly.

 

From what I've read and tried, it seems you can only set the service tag once, after that it's locked in.

 

Anyone know of a tool to do this? I have heard tell of various magical engineer tools, but can't find any current ones available for download.

[Ditto]

Watching, as I'm sure I grappled with this on some Optiplex 390/790's a while back. Can't remember if I cracked it - will look later, but have a feeling it did come down to one of those well hidden engineer exe's. I think from a quick Google search, I learnt the asset tag could be changes, but maybe not so easy for service tag.